Re: [PATCH v2 11/11] arm64: kernel: Add support for hibernate/suspend-to-disk.

[Pavel Machek <pavel@ucw.cz>]

On Mon 2015-11-16 14:01:04, James Morse wrote:
> Hi,
> 
> On 16/11/15 12:41, Pavel Machek wrote:
> >> On 14/11/15 21:34, Pavel Machek wrote:
> >>>> The implementation assumes that exactly the same kernel is booted on the
> >>>> same hardware, and that the kernel is loaded at the same physical address.
> >>>
> >>> BTW... on newer implementations (and I have patch for x86, too), we
> >>> try to make it so that resume kernel does not have to be same as
> >>> suspend one. It would be nice to move there with arm64, too. 
> >>
> >> Yes, that is a neat trick, can I leave it as future work?
> > 
> > Yes. But it is really not hard.
> 
> I think its harder than it looks:
> It means the MMU has to be turned off, as two different kernels may not
> have used the same configuration for the MMU - and I don't think its safe
> to change while the MMU is running. There are also going to be
> complications with resetting the hypervisor/el2 configuration, which I need
> to spend more time thinking about (and probably ask for advice!).

Well, you can simplify it here: If MMU configuration is stable between
4.3, 4.4 and 4.5 kernels, you just use suspend signature for 4.3-like
kernels. If you need to change it in future, you change the signature.

(If it changes too often, this might not work).

Best regards,
									Pavel
-- 
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